Gamma globulin is widely used as a therapeutic agent, and generally, it is administered by intramuscular injection. Impurities, such as aggregates of gamma globulin occasionally contained in gamma globulin products, render hazardous the administration of such gamma globulin products by intravenous injection.
Accordingly, for the purpose of preparing gamma globulin compositions free of aggregates thereof, there have been proposed methods of preparing gamma globulin under such conditions that aggregates are not produced. There have also been proposed methods of removing any aggregates that are produced in the course of preparing the gamma globulin, which removal takes place at the last step of the procedure. Such methods for the production or purification of gamma globulin have been disclosed in the literature, for instance, U.S. Pat. Nos. 3,415,804, 3,763,135 and 4,093,606, and British Pat. No. 1,372,953.
It is an object of this invention to provide a method of preparing gamma globulin, not containing aggregates of gamma globulin, under conditions different from those disclosed in the patents mentioned above.
The inventors have found that gamma globulin products containing albumin in certain quantities can be obtained by treating a supernatant liquid, separated from human blood plasma, with ethanol, under selected conditions as described in the following. In the invention process, the production of gamma globulin aggregates can be prevented, and gamma globulin products suitable for intravenous administration can be obtained in a high yield, which products contain a certain small quantity of albumin and do not contain gamma globulin aggregates. The present invention is based on this discovery.